Process for transferring heat from gases to other gases



Aug. 13, 1929. F. POLLITZER 1,724,513

PROCESS FOR TRANSFERRING HEAT FROM GASES TO OTHER GASES Filed Oct. 23. 1926 F. .9 f y] b, If A a c e e -P I I P f ab p f 'A A V 5 ,7 6 17 'INVENTOR Patented Aug. 13, 1 929.

UNITED STATES P AT-ENT OFFlCE.

FRANZ POLLIT ZER, OF GEOSSHESSELOHE, NEAR IU'NICH, GERMANY.

PROCESS FOR TRANSFERBING HEAT FROM GASES TO OTHER GASES.

Application m October 2a, 1926, Serial No. 148,674, and in Germany July 31,1925. 1

For the purpose of transferring heat from gases to other gases one of the following two ways is generally in use: either the gases are conveyed in a'counter-c u-rent through 5 tubes, the heat being transferred by the walls of the tubes from one gas to the other one; or the heat is transferred by the aid of solid materials, over which the gases are 'alternately conducted, separated from each other,

and which absorb the heat from the hot gases and transfer it to the @ld ones. The first mentioned manner of operating requires large surfaces for transferring the heat and consequently voluminous and expensive exchangers. In many cases, for .instance when air or other gases with a high relative humidity are to be cooled, the tubes will be obstructed by ice which cannot be removed without an interruption of the operation. The process above mentioned in thesecond place may be carried out with an apparatus relatively simple and less expensive, but in this case a device for interchanging the flow of gases and a rather complicated control are required.

The invention consists in a process for transferring heat from gases to other gases by which the above mentioned disadvantages are avoided. According to the invention the transmission is effected by the aid of a liquid.

By a circulation process this liquid is simcessively brought into direct communication with the gases to be treated. The utilization of liquid as an auxiliary body, which is- B driven through the cycle by means of a pump, has the advantage, that it thereby becomes possible to work in an absolutely continuous manner; on the other hand by driz- 1 zling a 1i uid over a'gas, the transfer of heat 10 is efi'ecte in a very advantageous manner.

A further advantage of this manner of operating is to be seen in the fact that it may be carried out by the aid of a simple apparatus of relatively small dimensions.

The carrying out of the new-process will" now be described by way of example by reference to the accompanying drawings.

Fig. 1 shows diagrammatically an arrangement for carrying out the invention wherein the heat exchange is from a compressed gas to an expanded gas, while Fig. 2 shows diagrammatically a modification of this arrangement.

Figure .1 illustrates the case of the exchange of heatfrom a compressed gas to an ing the column expanded gas, for instance for the purpose of liquefaction, and assuming as the object I of the liquefaction. a refrigeration output at the'temperature ofthe methane under at-l mospheric pressure. We choose as an ex-. ample the liquefaction of ethylene, using 3 toluene as an auxiliary liquid. The compressed ethylene enters the first colunm 'A at the temperature of cooling water, leaves the column at its higher end band is ex anded to the pressure of one atmosphere by t e regulatlng valve V. The gas thus cooled by expansion enters the second column B at c in which it will ascend and cool the descending liquid. Now, inasmuch as this cooling is transferred to the liquid trickling down in tower B, and since the latter (i. e. the liquid) thus pre-cooled yields its cold-in tower A to the gas flowing .to valve V,'it will be. seen that the temperature fall occasioned by expansion leads to lower temperatures in the rear of the valve V'than previously. This, in turn, leads to greater cooling of the liquid 1n B, and thus to further pre-cooling of the gas in A; the temperature on both sides of valve V decreases steadily until, when a state of stability is attained, liquefaction of the gas is produced-in the rear of V. The cooled toluene runs from the container 6 to a pump P, where it .will be brought to the pressure of the compressed ethylene. ,Then it is introduced into the columnA at f in which it I cools the compressed ethylene. When leav- A at the lower end by g, it

has approximately the initial temperature of the ethylene entering at a. Now the gas is brought to the upper end of the column B (at h) by the aid of an expansion valve D Th described apparatus has a mode of operating similar to that of the well-known counter-current apparatus provided with two or more tubes. When the upper'column has reached a low temperature the non-liquefied part of the ethylene enters the apparatus at c at the temperature of its boiling-point. The quantity of the circulating liquid must be regulated in such a manner thatit is suffici ent to heat the gas passing through the column B u to ordinary temperature. In the column the liquid may then absorb the same quantity of heat from the compressed gas passing the column. v

' The auxiliary liquid must consist of a inaterial which meets the following requirements. On the one hand it is necessary that temperature and onvand conveyed through the valve columns in the same manner it will not become too viscous atthe lowest the other hand it must have such a vapour-tension at the highest temperature that the escape of material will not cause a considerable loss. The evaporated quantities are to be, continuously replaced by addition of further liquid from a container E. It may also be advisable to recover the vapour passing off; together with the gas, for instance by absorption or dissolution. p

' In cases where a liquid of the desired qualities is not at disposal, two or more liquids should be used for the different ranges of temperature and two or more devices 0 the described kind should-be arranged one after the other. It is also possible to combine the described apparatus with a countercurrent of another kind of construction for ditl'orent ranges of temperatures.

In order to obtain a complete heat-exchange of liquid and gas, thehea't. capacity must be regulated in such a manner that it will be approximately equal at all temperatures. 11 the specific heat of the liquid decreases at lower temperatures in a quicker manner than that of the gas, as it may be often the case, this diminution may be equalized by increasing the quantity of circulat' ing liquid inthe cooler parts of the column. This mode of operating is illustrated by Fi 2. The liquid is partially. passed off at g D to the column B at 11,. The remaining liquid passes through the whole lengthof the two as shown in Figure 1. In cases where more than two gases are to be treated, it, is: necessary to provide for a corresponding. number ofcolumns, so that a special column is available for each gas.

Having now particularly described and ascertained the nature of my saidinvention,

warm liquid weenie what I claim and desire to secure by Letters Patent of the United States is:

. 1. A process for transferring heat from gases to other gases which comprises causing a; compressed gas to ascend through a descending shower of a cool liquid in a cooling chamber. expanding said gases thereby further cooling the same and causing said gases to ascend through a descendin shower of a warm liquid in a second chamber.

2. A process for transferring heat from gases to other gases which comprises causing a compressed gas to ascend through a descending shower of a cool liquid in a cooling chamber, expanding said gases thereby further cooling the same, causing said gases to ascend through a descending shower of a.

in a second chamber, thus cooled by heatexchange with the expanded gases being forced into the first mentioned chamber, descending therein in heat exchange with said compressed "as before expansion and returning said liquid for use in 'said second chamber.

3. A process for transferring heat from gases to other gases which comprises causing a compressed gas to ascend through a. descending shower of a cool liquid in a cooling chamber, expanding said gases thereby further cooling the same, causing 'said gases to ascend through a plurality of vertically spaced descending showers of a warm liquid in a second chamber, said liquid thus cooled by heat exchange with the expanded gases being forced into the first mentioned cham- .ber, descending "therein in heat exchange with said compressed gas before expansion and successfully withdrawing said llqu'id at vertical intervals from said first chamber and returning the same to corresponding showers in' said second chamber.

FRANZ POLLITZER.

said liquid- 

